This application claims the priority of Korean Patent Application No. 2003-71444, filed on Oct. 14, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a simple method of preparing 1,4,6-substituted, 1,4-substituted, 1,6-substituted, or 1-substituted fulvene compounds, and a novel intermediate derived from the method. Also, the present invention relates to a method of preparing an ansa-metallocene compound using the fulvene compound and the novel intermediate. Particularly, the present invention relates to a simple, mass-producible method of preparing an ansa-metallocene compound having substituents only at positions adjacent to the bridging point of cyclopentadienyl ligand(s).
2. Description of the Related Art
The ansa-metallocene compound can be vitally used as an olefin polymerisation catalyst.
The ansa-metallocene catalyst having substituents only at positions adjacent to the bridging point was proposed by the present inventor. The present inventor demonstrated that an excellent performance is obtained when a monomer having high steric hindrance, such as a norbornene, is copolymerised with an ethylene, due to low steric hindrance at reaction point, by the ansa-metallocene catalyst. See Korean Patent Application No. 10-98-12658; Organometallics, 2002, 21, 1500–1503 and J. Organomet. Chem., 2002, 660, 161–166. However, as shown in Reaction Scheme I below, the preparation method is not easy one, and thus has a problem in mass production. Particularly, the synthesis of 1,4-pentadiyne, a starting material of the preparation process of the ansa-metallocene catalyst, is not commercially available. A serial procedure consisting of incorporating a substituent via Pauson-Khand reaction by using the starting material and performing the reverse Diels-Alder reaction is performed at a stringent condition, such as high temperature or high pressure, has many reaction steps, and needs separating-purifying operation by chromatography method, etc. for the intermediates of each reaction steps. Further, the Reaction Scheme has disadvantage that the process use excessive amounts of methyllithium which is dangerous and expensive. Accordingly, the catalyst cannot be easily prepared in commercially significant amounts by Reaction Scheme I below, due to such reasons.

For the method of more easily preparing the metallocene catalysts having a substituent at positions adjacent to the bridging point, the method of preparing 1,4,6-substituted, 1,4-substituted, 1,6-substituted, or 1-substituted fulvene compound according to Reaction Scheme II below (Korean Patent Application No. 10-2002-51425) and the method of preparing the metallocene catalyst according to Reaction Scheme III by employing the former method (Korean Patent Application No. 10-2002-51426) have been filed previously.

However, the preparation steps are also too complicated for this case. Particularly, these include protecting-deprotecting steps which are not preferable for mass production such as protection of a ketone to a ketal, organometallic reaction, and then deprotection of the ketal. Further, even though various metallocene catalysts can be prepared by the Reaction Scheme III from the new fulvene prepared by the Reaction Scheme II, the compound A of the Reaction Scheme I cannot be prepared. According to the patent applications, a novel metallocene compound is prepared by preparing a ligand through nucleophilic attack of a cyclopentadienyl, an indenyl, a fluorenyl, an amido, a phosphino anion or their derivatives to a fulvene, and then attaching a metal to the ligand. Reaction of 1,3-dimethylcyclopentadienyl anion is with a 1,4-dimethylfulvene, for the purpose of preparation of the compound is A of the Reaction Scheme I, affords a compound having methyl groups at 1- and 4-positions according to the rightward direction in the Reaction Scheme IV below due to the steric hindrance effect, instead of the desired ligand by the reaction of leftward direction of the scheme.

For the same reason, incorporation of monosubstituted cyclopentadienyl anion into the fulvene shown in Reaction Scheme V below will afford a ligand having a substituent at β-position instead of a ligand having a substituent at α-position.

The present invention provides the methods capable of overcoming two problems described above. The present invention provides a method of preparing 1,4,6-substituted, 1,4-substituted, 1,6-substituted, or 1-substituted fulvene compound in short steps without protecting-deprotecting procedures. Further, the present invention provides a method of easily preparing a metallocene compound having a substituent only at positions adjacent to a bridging point as shown in the Reaction Schemes IV and V.